ELECTRONIC ADD-ON MODULE FOR INJECTION APPLIANCES

Abstract

The invention relates to an electronic add-on module which is fitted releasably onto an automatic injection appliance before the start of injection. The add-on module comprises a force sensor for measuring a time-variable axial force component exerted on or transmitted to the attached add-on module by the injection appliance during an injection procedure. The add-on module also comprises a grip or a preferred grip position for gripping and holding the add-on module and the inserted injection appliance. The add-on module can additionally have a microphone for detection of acoustic signals. A state of the injection appliance can be determined by the add-on module solely on the basis of measurements of the axial force sensor, optionally supplemented by microphone measurements. The invention thus affords a straightforward and cost-effective way of monitoring or controlling the correct performance of an injection procedure carried out with an automatic injection appliance.

Claims

1. Add-on module for fitting to an injection appliance with a longitudinal axis, comprising: a force sensor for measuring a force component in the direction of the longitudinal axis exerted by the injection appliance on a fitted add-on module during an injection procedure; and a grip for holding the injection appliance and the fitted add-on module.

2. Add-on module according to claim 1, further comprising an appliance holder, which at least partially encloses the injection appliance in a fitted state, wherein the grip encloses the appliance holder and, in the direction of the longitudinal axis, has an extension of at least half the user's hand width.

3. Add-on module according to claim 2, further comprising a holding mechanism, which fixes the injection appliance in the fitted state in the direction of the longitudinal axis.

4. Add-on module according to claim 1, further comprising evaluation electronics to evaluate measurements of the force sensor for the purpose of identifying a procedure or a state of the injection appliance.

5. Add-on module according to claim 4, wherein the evaluation electronics are configured to identify a movement of a stop element of the injection appliance.

6. Add-on module according to claim 4, wherein the evaluation electronics are configured to identify a stop movement of a stop element signaling the start or end of dispensing.

7. Add-on module according to claim 4, wherein the evaluation electronics are configured to generate a multivalent event pattern from a measured impetus signal and to compare the generated multivalent event pattern with a basic pattern.

8. Add-on module according to claim 4, further comprising a microphone to measure an acoustic signal from the injection procedure, and wherein the evaluation electronics are configured to identify a movement of a stop element of the injection appliance based on the microphone measurements.

9. Add-on module according to claim 5, further comprising a microphone to measure an acoustic signal from the injection procedure, wherein the evaluation electronics are configured to identify a movement of a stop element of the injection appliance signaling the start or end of dispensing based on the microphone measurements.

10. Add-on module according to claim 1, further comprising a wireless communications unit to communicate with a mobile device, and/or a status display in order to display a status of the injection appliance.

11. Injection system with an injection appliance and an add-on module according to claim 1, where the injection appliance has a needle protection sleeve spring, which is compressed during a piercing process, wherein the add-on module is configured to identify a piercing process from an increase in an axial force measured by the force sensor to a value that is at least approximately constant and brought about by the compressed needle protection sleeve spring.

12. Injection system according to claim 11, wherein the needle protection sleeve spring accelerates a stop element at the end of dispensing and the add-on module is configured to identify a stop of the accelerated stop element from an impetus detected by the force sensor.

13. Injection system according to claim 12, further comprising an appliance holder, which at least partially encloses the injection appliance in a fitted state, wherein the grip encloses the appliance holder and, in the direction of the longitudinal axis, has an extension of at least half the user's hand width.

14. Injection system according to claim 12, further comprising a holding mechanism, which fixes the injection appliance in the fitted state in the direction of the longitudinal axis.

15. Injection system according to claim 12, further comprising a holding mechanism, which, via a pre-stress path in the module housing between a holding device and the force sensor, fixes the injection appliance in the fitted state in the direction of the longitudinal axis and applies a preload or a pre-stress force to the force sensor.

16. Injection system according to claim 12, further comprising evaluation electronics to evaluate measurements of the force sensor for the purpose of identifying a procedure or a state of the injection appliance.

17. Injection system according to claim 12, further comprising a microphone to measure an acoustic signal from the injection process, and the evaluation electronics are configured to identify a movement of a stop element of the injection appliance signaling the start or end of dispensing based on the microphone measurements.

18. Add-on module for fitting to an injection appliance, comprising evaluation electronics configured to identify processes in the injection appliance or states of the injection appliance during an injection procedure, based on sensor measurements brought about by movements of a user of the appliance or by a released drive mechanism or by other movements of components of the injection appliance.

19. Add-on module according to claim 18, wherein the sensor is a force sensor or an acoustic sensor.

20. Add-on module according to claim 18, wherein the sensor is a force sensor making a first measurement and the module further comprises a type of sensor that is different from the force sensor performing a second measurement, where both measurements are jointly evaluated to identify an event of the injection appliance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following preferred embodiments of the invention are described below in connection with the attached figures. These are to highlight the fundamental possibilities of the invention and must not be interpreted in a restrictive manner.

[0020] FIGS. 1A-1B show an injection system with an injection appliance and an add-on module; FIG. 1C shows these fitted together;

[0021] FIG. 2 shows an injection device in longitudinal section;

[0022] FIG. 3 shows an exploded view of an add-on module;

[0023] FIG. 4 shows the measured signals of a force sensor (top) and a microphone (bottom) in the add-on module;

[0024] FIG. 5 shows a diagram of the evaluation electronics of an add-on module;

[0025] FIG. 6A shows a signal measured through a force sensor and FIG. 6B shows it as filtered;

[0026] FIGS. 7A-7E show an event pattern formation from an impetus signal; and

[0027] FIG. 8 shows an enlarged medical monitoring system.

DETAILED DESCRIPTION

[0028] FIGS. 1A-1C show an injection system with an injection appliance 1 and an add-on module 2, both in a separate state (FIG. 1A-1B) and in a fitted, mounted, combined or coupled state (FIG. 1C). The injection appliance has a long device housing 10 that is symmetrical around a longitudinal axis, and a needle protection sleeve 11 that can be displaced between a first position shielding a needle of the injection appliance (shown in FIG. 1) and a second position exposing the needle. A needle protection cap remover 12 in its delivered state is fitted to a distal end of an injection appliance and, prior to injection, has to be removed or pulled off together with a needle protection cap that mechanically protects the needle. The add-on module has a long, sleeve-shaped module housing 20 with a hollow space as an appliance holder for the injection appliance, said appliance holder being matched to the external shape of the appliance housing, so that the injection appliance can be inserted into the add-on module for coupling purposes. The add-on module has a release button 24a of a holding device, an optical status display 23c, 23d for a visual feedback to the user, and side openings 20a, which, in the fitted state, are aligned to windows 10a in the appliance housing and make it possible to see a substance that is stored in the injection appliance. Alternatively, the add-on module can also be distinctly shorter than the injection appliance, in other words, only about two thirds or just about half as long. On the outside, the module housing has a grip 21 with a slightly concave grip position, which comprises a slightly raised portion 21a as the distal grip limit or an area of increased diameter in order to make easier absorption of user force in the distal direction.

[0029] At the start of the injection, the distal end of the injection appliance, i.e., the needle protection sleeve, is pressed onto the injection site by the user so that the needle protection sleeve is inserted, under compression of the needle protection sleeve spring, in a proximal direction, into the injection appliance, and at the same time, the needle penetrates the injection point. In order to guarantee that in every case the user transmits the force to the injection appliance throughout the injection process, including release and execution of dispensing by means of the add-on module, the add-on module is developed as a sleeve over a major part of the injection appliance. The injection appliance can therefore not be unintentionally held. A clear width or an internal diameter of the appliance holder is larger, at least in the area of the grip, by an amount of a few tenths of a millimeter above the manufacturing tolerances than an external diameter of the injection appliance. In other words, the add-on module has some radial play in relation to the injection appliance so that they can move without friction in relation to one another and the entire force is transmitted through the force sensor.

[0030] FIG. 2 shows the longitudinal section of an injection device in a state prior to injection, in which a syringe 13a with needle 13b filled with a substance to be dispensed is used. A proximal end of a hollow cylindrical needle protection sleeve 11 is in contact with a rigid locking sleeve, which in turn is adjacent to a needle protection sleeve spring 14. At the proximal end of the needle protection sleeve spring, an initial stop element or click element 15a is provided to mark the end of dispensing (end of injection, EOI). At the start of dispensing, a piston rod is connected to the first stop element by way of cams so that the first stop element can be moved forward by a small stroke at the start of dispensing, thereby further compressing the needle protection sleeve spring. Following complete dispensing of the substance and conclusion of the forward movement of the piston rod, the first stop element is released and accelerated proximally backward by the needle protection sleeve spring, where it strikes an end cap and generates a clicking sound which can be clearly heard by the user, and a noticeable knock. A second stop element 15b or click element is provided to mark the start of dispensing (start of injectionSOI). Initially, a click pin is interlocked with the piston rod to prevent any relative movement. When triggering dispensing by proximally displacing the needle protection sleeve and the locking sleeve, the piston rod and click pin are released and are forced apart by a pre-compressed injection spring 16. This movement by the click pin is transmitted to the second stop element, so that the proximal end of the second stop element strikes the end cap and generates a clearly audible clicking sound and a force surge or impulse.

[0031] As an alternative to the simultaneous insertion of the needle protection sleeve and needle piercing, a syringe that is slidably mounted in the injection appliance and that is surrounded in its delivered state, including the needle point, by the appliance housing, can be moved by the force of a piercing and/or dispensing spring relative to the appliance housing. This automatic piercing movement is triggered following a partial or complete insertion of the needle protection sleeve into the injection appliance. The impact of the accelerated syringe on a stop element likewise causes a distinct impetus followed by a roughly constant holding or dispensing force. The preceding insert movement of the needle protection sleeve with simultaneous compression of the needle protection sleeve spring can take place slowly and, in the case of a pre-compressed needle protection sleeve spring, possibly only after the spring biasing force has been overcome. The movement may result in a continuous rise in measured axial force, possibly by applying a minimal unlocking or injection blocking force that can be seen in the force curve and is superimposed on the spring compression force.

[0032] In a further embodiment, the piercing movement can also be started by a release button operated by the user.

[0033] FIG. 3 shows an exploded view of an add-on module according to the invention. The module housing comprises a first housing half 20b and a second housing half 20c that are snapped onto a module sleeve 20d. In an electronics holder 23a, in the rear section of the add-on module, is accommodated the module electronics, comprising a force sensor 22 or a pressure sensor, a contact switch 23b to detect complete insertion of the injection appliance into the add-on module, a connection status indicator 23c to signal successful establishment of a connection to a mobile device 31 (see FIG. 8), a status display 23d with LEDs and light guides in the form of a transparent, distal sealing cap 26. Also provided are a microphone 23e, a battery 23f as energy source, a buzzer or loudspeaker 23g to generate sounds, and a communications unit 23h with a Bluetooth Low Energy (BLE) chip including an evaluation unit for signal processing and data storage. The status display may, in particular, show the following states: add-on module fitted, add-on module ready, injection running, injection ended, holding time elapsed, remove add-on module, BLE status. The status display can also emit warnings, such as add-on module incorrectly fitted, add-on module switched off because of inactivity, battery status low, reminder to remove add-on module, or even error messages such as end of injection during dispensing, ending injection during holding time.

[0034] A holding device or holding mechanism comprises an annular transfer element 24b guided in the module sleeve, a holding structure or nose securely fitted to the transfer element, a latching spring that moves the transfer element 24b together with a holding structure into a holding position, and a release button 24a as an operating element to move the transfer element 24b and to release the holding structure from the holding position. In the holding position, the holding structure is latched in a recess 25, such as a notch or slit in the injection appliance housing. This recess can also be used for other purposes and is ideally already available in existing injection appliances, which means that no adjustment has to be made to the injection appliance in order to use the add-on module. As an alternative to pressing on the release button and moving the transfer element perpendicularly to the longitudinal axis, the operating element can also perform a sliding movement. When the holding structure is released, the injection appliance can slide out of the add-on module in the axial direction, so that the holding mechanism makes it possible to snap the add-on module onto the injection appliance such that it can be detached. The module housing in FIG. 3 is distinguished from that in FIG. 1, in particular by the arrangement of the holding device within the grip area instead of between the grip area and the distal housing end. The holding device is therefore gripped by the user during holding, and the release button in this case is slightly recessed in the module housing so as to prevent accidental release by the user's holding hand.

[0035] The holding device may have slight play through the corresponding design of the holding structure and recess 25 in the axial direction, so that the force sensor 22 can move away from the end cap or contact surface. In this case, the force sensor 22 is not pre-stressed when the injection appliance is not placed on the injection site and the needle protection sleeve spring is not compressed. Accordingly, a signal or click at the end of dispensing following premature removal of the injection appliance may possibly no longer be detected by the force sensor, so that only acoustic identification via the microphone can contribute to the completion of the defective injection process. On the other hand, by force-fit snapping in of the holding structure of the add-on module into the recess 25 of the injection appliance, the force sensor can also be pre-loaded or pre-stressed. In one such case, a pre-stress path in the module housing between holding device and force sensor is accordingly pre-stressed in tension and, under certain circumstances, only external axial forces can be observed at the force sensor above a certain pre-stress value. For example, an axial force sensor in contact with the proximal face of the injection appliance initially measures the pre-stress value as well as any small user force, which is dispersed to the rear, for example, by avoiding the pre-stress path. On the other hand, in the preferred arrangement of the grip as part of the module housing enclosing the appliance holder, the axial force of the user is at least partially led via the pre-stress path to the force sensor. As a result, the tension load in the pre-stress path is initially reduced, and only user forces above a minimum value that does not exceed the pre-stressing force are measured by the force sensor in addition to the pre-stressing force.

[0036] In the embodiment shown, the axial force sensor within the add-on module in its fitted state comes to rest against the proximal or rear end of the injection appliance. In other words, it makes contact with a proximal surface or end cap of the injection appliance, which represents a simplification compared with a transfer of force via a contact surface provided on the side of the appliance perpendicular to the axis, in other words, for example, via a proximal annular face of a surrounding flange or of a section thereof. Likewise, a diversion of the axial force by means of moving components on the add-on module in a direction that deviates from the longitudinal direction is conceivable, for example, for non-axial positioning of the force sensor.

[0037] Suitable force sensors are based on a piezo-resistive effect, in other words, on a change in the specific electrical resistance of a conductor when mechanically deformed. In the case of the Honeywell FSS series force sensors, the resistance of piezo-resistances incorporated in a silicon measuring element increase if said piezo-resistances are bent by force, which can be measured by a resistance bridge. The sensor transmits any force applied between zero and 20 N via a high-grade steel ball directly to the silicon measuring element, where the ball is moved by a maximum stroke of 50 micrometers. Alternative force sensors for measuring holding forces comprise strain gauges fitted to cantilever beams or FSR (Force Sensing Resistor) pressure sensors.

[0038] The evaluation unit can be integrated in the communications unit 23h or can be provided as an independent chip on the electronics holder. The evaluation unit processes the signals of the force sensor 22 and any further sensors provided, provides a time stamp, and determines consolidated injection information from the processed signals and relevant time stamps. The injection information includes at least information that an injection has been successfully carried out at a specific time, or what faulty actions have possibly been carried out. Such information is stored in a memory unit in the add-on module and/or forwarded via the communications unit 23h. The memory unit can also store identification data of the user or the add-on module.

[0039] In order to save energy, the contact switch 23b can also operate as an activation element to activate the add-on module from a power-saving mode. In addition or as an alternative, the energy source can be recharged, for which purpose the add-on module has a suitable plug connector or is provided with a charging station for inductive energy transfer. The charging station can only accommodate the add-on module or the add-on module with attached injection appliance and can also be used by other chargeable appliances of the user. An intelligent charging station can act as a base station and have additional functionalities, for example measuring the temperature of the attached injection appliance and/or of the medicament that it contains. If the injection appliance is placed in the charging unit following storage in the fridge and prior to use, such a temperature measurement at the injection appliance can issue a signal as soon as a minimum temperature for administering the medicament is reached. During the warming process, the energy source of the add-on module can also be recharged without any further intervention by the user. By way of a further communications interface, the intelligent charging station can also provide time and date information in order to synchronize a clock on the add-on module, or can adopt the consolidated injection information as a fallback level to the mobile appliance, as described below.

[0040] FIG. 4 shows the signals from a piezo-resistive force sensor (top) and an electret microphone (bottom) measured during a complete injection procedure lasting 20 seconds. The following events are assigned to the signals: (a) connecting add-on module and injection appliance, (b) removing the needle protection cap from the injection appliance, (c) moving/tilting the injection appliance to the injection site, (d) start of dispensing (start of injectionSOI), (e) end of dispensing (end of injectionEOI), (f) removing the injection appliance from the injection site, (g) placing the injection appliance in a horizontal position, (h) setting aside the injection appliance, (i) lifting and dropping the injection appliance, (j) removing the injection appliance from add-on module. The drop in force of the measured axial force when removing or withdrawing the injection appliance from the injection site (event f) is more continuous than when piercing (event d) and follows the releasing needle protection sleeve spring, possibly with formation of a peak superimposing the edge, caused by a movement of a needle protection sleeve locking mechanism.

[0041] States, processes and events in the injection appliance and during the injection process can be identified, as follows, by way of example, by combinational interlinking of the information from the force sensor and the microphone. In order to detect a start click, the combination of a clear acoustic peak and an increase in force (remaining on the force plateau) is required. In order to detect an end click, the combination of a clear acoustic peak and a consistently high force is demanded. Removal of the injection appliance together with the add-on module from the injection site is detected by the reduction in force after the end click. If the injection appliance is removed from the injection site before the end click or even during the required holding time, this can be detected by the premature drop in force.

[0042] FIG. 5 shows a diagram of evaluation electronics as part of the evaluation unit, to be applied to an input signal A measured by the force sensor. The low frequency signal components are filtered out in a high-pass filter with a cutoff limit of 200 Hz (FIG. 5, left). The filtered signal comprises both positive and negative peaks in line with the deviations in the impetus signal compared with a holding force plateau. In order to avoid negative voltage values, the output signal of the filter is raised to an offset of 2 V (half the supply voltage). The resulting signal B is fed to a comparator (FIG. 5, right), which compares the analog signal with an upper and lower limit value of an amplitude window and converts it into pulses. If the signal prepared in this way exceeds the upper limit value, then an initial comparator output value C, for example a pulse of plus 1 V, is emitted, or a corresponding bit or character is set. If the signal falls short of the lower limit value, then a second comparator output value D, for example a pulse of minus 1 V, is generated. Subsequently, a trivalent discrete event pattern is generated as a consequence of positive and negative pulses of different length, separated by a neutral or mid-value pulse of random length.

[0043] The evaluation electronics can be implemented in an analog, digital or mixed way. For example, the high-pass-filtered analog sensor signal is conveyed to a microprocessor, where it is converted into a digital signal and fed to the digital comparator function programmed in the microprocessor memory. A scanning rate for digitizing the impetus signal must be selected according to Nyquist. For an impetus signal corresponding to an acoustic click sound with a frequency spectrum of up to 5 kHz, scanning every 20 microseconds is therefore appropriate.

[0044] FIG. 6 shows an input signal A measured by a force sensor at the input of a filter, as well as the filtered signal B at the input of a comparator generated by filtering signal A. The entire process depicted lasts for 5 seconds. Accordingly, the impetus signals at the start and end of dispensing, corresponding to a start-of-injection and end-of-injection click, can only be detected as narrow peaks.

[0045] FIG. 7 shows an example of event pattern formation for the impetus signal at the start of dispensing in FIG. 6, which undergoes resolution over a period of 8 milliseconds. The unfiltered signal A and the filtered signal B show correspondingly more structure. By comparing signal B with an initial limit or threshold value shown by the upper horizontal line G1, an initial comparator output signal C is generated with three pulses of different length. By comparing signal B with a second limit or threshold value shown by the bottom horizontal line G2, a second comparator output signal D is generated, in this case comprising a sequence of four pulses of different length. The consequence of the second pulses is shown as negative values for the sake of better legibility. The resulting event pattern from the selected pulse with the two components C and D coincides with the characteristic basic pattern or the signature of a start click, shown by the curve E, to the extent that the three pulses of the basic pattern are completely within pulses of the event pattern in terms of time. Accordingly, the impetus signal is identified as coming from a start click. The limit values G and the relevant basic pattern E are preferably determined by an iterative procedure with repeated recording and analysis of impetuses of known origin. The selected limit values then ideally result in minimum scattering in the event patterns and hence to a high degree of reproducibility. The algorithm introduced can successfully identify or rule out previous actions and incorrect handling, such as lifting the add-on module, assembling the add-on module, removing the needle protection, turning, dropping, loud ambient noises, and shaky holding as impetuses that are not relevant to injecting and do not coincide with any basic signal.

[0046] FIG. 8 shows an expanded medical monitoring system with an injection appliance 1, an add-on module 2, a mobile display and output unit 31, which can communicate wirelessly with the add-on module and an optional, fixed data processing system based on delocalized data storage (cloud computing), or expert system 32. The add-on module transmits data (indicated at signal 40) from an injection process and/or consolidated injection information wirelessly to a compatible mobile device, for example, to a smartphone having a special application or to a duly configured portable computer.

[0047] The mobile device must be initially set up and configured, for example, by installing an application and registering the user 42. This can be done by a patient data card that transcribes all the relevant data onto the mobile device 31 using near-field radio communication (NFC) or optical QR codes. If the mobile device 31 is located within range of the add-on module, then this data transmission can take place in real time during an injection procedure or only once it is completed. In the first case, the mobile device 31 can issue instructions to the user 42 in real time and thereby guide the user through the next steps. In all events, the injection information may also be stored in the add-on module 2 and only transmitted later in consolidated form. The data received from the mobile device 31 can be supplemented by the user 42, for example by indicating the injection site, and are passed on in a suitable way to the expert system. The latter stores the data and provides patients, medical staff and health insurers with targeted information, and in this way assists the user of the injection appliance in following a treatment plan.

REFERENCE LIST

[0048] 1 Injection appliance [0049] 10 Appliance housing [0050] 10a Window [0051] 11 Needle protection sleeve [0052] 12 Needle protection cap remover [0053] 13a Syringe [0054] 13b Needle [0055] 14 Needle protection sleeve spring [0056] 15a, 15b Stop element [0057] 16 Dispensing spring [0058] 2 Add-on module [0059] 20 Module housing [0060] 20a Opening [0061] 20b, 20c Housing halves [0062] 20d Module sleeve [0063] 21 Grip [0064] 21a Grip limit [0065] 22 Force sensor [0066] 23a Electronics holder [0067] 23b Contact switch [0068] 23c Connection display [0069] 23d Status display [0070] 23e Microphone [0071] 23f Battery [0072] 23g Buzzer [0073] 23h Communications unit [0074] 24a Release button [0075] 24b Transfer element [0076] 25 Recess [0077] 26 Add-on cap [0078] 31 Mobile device [0079] 32 Data processing system [0080] 40 Transmitted signal [0081] 42 User